Water repellent treatment for masonry and silexane composition



Uniwd a es Patent Shailer L. Bass, Midland, Mich assignor to Dow CorningCorporation, Midland, Mich., a corporation of Michigan No Drawing.Application June 21, 1951, Serial No. 232,860

9 Claims. (Cl. 260-465) The present invention relates to methods andcompositions for rendering masonry water repellent.

Heretofore methods for rendering masonry water repellent'have involvedtreatment with materials such as paraffin and a drying oil, aluminumstearate, oleoresins in vegetableoil vehicles such as linseed oil, andemulsions of various resins, usually with plasticizers, such as polyvinyl acetate and polystyrene.

The ideal above grade masonry water repellent, however, shouldincorporate a combination of a number of features, and the prior artmethods have invariably been satisfactory with regard to only a few ofthe desired properties. The desirable properties are: (1) Long life (inexcess of one to three years. A short life is one of the chiefshortcomings of the present commercial prod ucts. (2) Deep penetration.This requirement is closely related to long life, for weathering at thesurface does not destroy the water repellency of a deeply penetratingtreatment. (3) Quick development of water repellency. Thischaracteristic is important in cases of hard rain shortly afterapplication. (4) No tendency to clog pores of masonry. This is importantbecause a treated surface should have the ability to breathe or transmitwater vapor. (5) Clear and invisible film, causing no change in color orcharacter of masonry. (6) The treated surface should be capable of beingpainted over and bonding tightly to the dried paint film. (7)Application should be possible even at the lowest practical workingtemperatures (as low as F.). (8) Solubility in inexpensive solvents,allowing economical application. (9) Easy to apply by spraying orbrushing.

The general water-repellent properties of organo-polysiloxanes areknown. Certain compositions comprising these siloxanes have met with acertain degree of success as clear masonry water-repellents. Theseorganosiloxane compositions, however, have found lacking in several ofthe desirable properties listed above. The known materials have tendedto be either too slow in the development of their water repellentproperties, have given too low a degree of water-repellency, or else areare subject to a too rapid deterioration upon weathering and aging.

It is an object of the present invention to provide an improved and moreeconomical method and composition for rendering masonry surface waterrepellent, said method and composition containing in combination thedesirable features listed above.

The essential ingredient of the composition of this invention is apartial hydrolyzate of an alkoxylated mixture of by-productchlorosilicon compounds obtained from the reaction of CHsCl and Si, saidpartial hydrolyzate containing from 20 to per cent by weight alkoxy.

The aforesaid reaction of CHsCl and Si is conducted within thetemperature range of 200 to 500 C., preferably with copper as a catalystgiving CHsSiCla and (CH3)2SiCl2 as the major products. This method isdisclosed in detail in U. S. Patent No. 2,380,995. A hydrogen halide maybe used in conjunction with the CHsCl in this process to give improvedyields, as disclosed in U. S. Patent No. 2,488,487. Commercial use ofthe prodnets of this process has been limited strictly to use of theabove methylchlorosilanes obtained as the major prodnets.

The by-products of the aforesaid reaction are defined as the distillablechlorosilanes boiling above (CH3)2SiCl2, i. e. above 69.8 C. atatmospheric pressure. These byproducts are comprised of organicsubstituted and nonorganic substituted silanes, disilanes, disiloxanes,silmethylenes, and silethylenes; and a large portion of completelyunidentified organosilicon compounds. There is at present no knowncommercial method of separating these components into fractions of eventhe slightest degree of purity. This is because of the large number ofindividual silicon compounds present, the relatively small percentage ofeach, the close boiling points of the compounds, and the presence of avariety of by-produced hydrocarbons which boil throughout the boilingrange of the silicon compounds. Consequently the fractionation of thesematerials through even the best of laboratory distillation columns, withsubsequent redistillation of selected portions of the distillate, hasresulted in the isolation an identification of only a comparative few ofthe compounds present. Table 1 lists the few known compounds and theirapproximate boiling points found in the by products of a representativeindustrial scale reaction of CI-laCl-l-Si. The boiling points are indegrees centigrade at atmospheric pressure.

TABLE I Compound: B. P., C. Benzene 2-methylhexane B-methylhexane 91Methylcyclohexane 99 Ethyltrichlorosilane 100 Ethylmethyldichlorosilane102 Toluene 1 10 Hydrocarbons 1 1 11 16 Isopropyltrichlorosilane 1 l 8isopropylmethyldichlorosilane 15 n-Propyltrichlorosilane 124n-Propylmethyldichlorosilane 125 Hexachlorodisiloxane 128 Ethylbenzene134.6 CHsClzSiOSiCls Isobutyltrichlodosilane 141.5 Hexachlorodisilane146 (CH3)2ClSi-SiCl3 157 CH3 ClaSiOSiClzCHs 158 Ethyltoluene 162Diethylbenzene CH3 2ClSiCH2SiCl CH3 2 178 (CH3 2ClSiCH2SiCl3Cl3SiCH2SiCl3 1 85 Cl3SiCH2SiCl2CH3 189 CHsClzSiCHzSiCl-zCI-Is 192C6H5SiCl3 201 CH3Cl2SiCH2CI-I2S1Cl3 206 The relative proportions presentof the above identified compounds are unknown, for only a few grams ofeach pure material can be isolated from large quantities of the startingmixture of by-products. This is due to the fact that a firstdistillation of the mixture gives a distillate of gradually increasingboiling point. There are none of the usual plateaux of constant boilingmaterial present in the distillate. Repeated fractionations of selecteddistillate fractions are necessary to obtain small portions ofrelatively pure material. The identity of the material boiling betweenthe various identified compounds has not been established. The mixtureof by-products ordinarily has an atomic ratio of hydrolyzable C1 to Siranging from 2.311 to 2.7:1.

The by-products of the CHsCl-l-Si reaction represent an economical buthitherto untapped source of organosiloxane polymers. The utilization ofthese by-products has been complicated by the diversity and number ofindividual components therein. As has been shown above, the boilingpoints of the individual components 3 are so close to one another thatseparation is impossible on a commercial scale.

It has been found, however, that after CH3SiCl3 and (CH3)2SiCl2 havebeen removed from the reaction products of CHaCl and Si, the remainingdistillable silane byproducts can be separated from the non-volatileresidue, as for example by flash distillation. The entire mixture ofsaid by-products can then be alkoxylated and partially hydrolyzed in aparticular fashion to produce an organosiloxane copolymer which is notonly relatively economical, but which is also a superior masonry waterrepellent.

The reasons for the superiority of this material are not at allapparent. The polymeric structure is unknown, for the nature andproportions of many of the starting chlorosilanes are unknown. It isonly known that the copolymers obtained by the hereinafter describedprocedure give improved results when applied to masonry, as compared tothe best of the hitherto known masonry treatments.

For purposes of this invention, copolymers are prepared from theby-products of the CHsCl-l-Si reaction in the following manner.

' Substantially all of the CHsSiCla and (CH3)2SiCl2 are first removedfrom the reaction products of the CH3Cl+Si reaction. In the usualindustrial distillation, this leaves a residue which may contain up toper cent by weight, but usually less, of material boiling at or belowthe boiling point of the (CH3)2SiCl2. This residue is then furtherdistilled to obtain as a distillate, a mixture of essentially all thedistillable by-produced silicon compounds and hydrocarbons. v

The mixture of by-products is then reacted by contacting it with aprimary or secondary lower alkyl monohydric alcohol. The preferredalcohols are those of from 1 to 4 inclusive carbon atoms. The amount ofalcohol used is equivalent to at least 30 molar per cent of thehydroxyzable Cl attached to Si in the mixture of lay-products. Whenmethanol is used, the best results are obtained by employing an amountequivalent to, or slightly in excess of. the molar quantity ofhydrolyzable Cl present. Any excess used will of course not enter intothe reaction, but will be present as a solvent in the subsequenthydrolysis step. When alcohols having 2 or more carbon atoms are used,it is preferable to employ a quantity equivalent to from 30 to 80 molarper cent of the hydrolyzable Cl present in the mixture of by-products,although an equivalent amount may be used if desired. Thus when thehigher molecular weight alcohols are used in the alkoxylation step,thepreferred range employed leads to a mixture of alkoxychlorosilanes,whereas when methanol is used, it is preferable that the product beessentially completely alkoxylated. If desired, mixtures of the abovedefined alcohols may be used.

The alkoxylated product is then partially hydrolyzed by contacting itwith water. An inert diluent may be present in this step, but is notessential. The amount of water used is at least equivalent to the molardifference between the hydrolyzable Cl in the original by-product andthe amount of alcohol used, but is insufficient to completely hydrolyzemore than about 70 molar per cent of the total hydrolyzable groupspresent. Preferably the partially hydrolyzed product should, whenfinished, contain from about 20 to about 50 per cent by weight alkoxy.The physical properties of the resulting product will vary considerablywith the amount of water used. As greater amounts of water are used, theextent of. hydrolysis and subsequent condensation is increased and theviscosity of the product increases accordingly. These variableproperties, however, apparently have little if any effect upon theeffectiveness of the product as a masonry water repellent, as long asthepreparation is conducted within the defined limits.

If desired, heat may be applied to the partial hydrolyzate in order tospeed up the condensation reaction and to aid in the evolution of anyI-ICl which might be present. If any residual HCl remains in the partialhydrolyzate it is preferable that it be neutralized, as for instance bycontacting the hydrolyzate with NaHCOs.

The finished partial hydrolyzate product is a copolymer containing allof the various organosilyl substituents and unsubstituted siliconsubstituents present in the by-product mixture. The various Si atoms arelinked by methylene links, ethylene links, Si-Si bonding, andsiliconoxygen-silicon bonding, and as stated above the copolymer shouldcontain frornZO to 50 ,per cent by weight alkoxy. The copolymer may alsocontain a minor lymer is'soluble in the common organic solvents." Thetit) solvent-free copolymer is not a resin but is a fluid, which uponexposure to atmospheric moisture further hydrolyzes and condenses toform a non-tacky resin.

The compositions of this invention can be applied to all types ofabsorbent masonry and joints, as for example concrete blocks, brick,cinder block, sandstone, stucco, concrete, mortar, water-mixed cementcoatings, and water-mixed paints. Such application has been found torender the masonry highly water-repellent. It provides a long lasting,deeply penetrating colorless treatment which stops water seepage due tocapillary action, and thereby decreases staining and efilorescence onthe masonry. It helps preserve the masonry and saves inside and outsiderepair expenses.

In order to obtain maximum penetration of the treatment and to extendthe coverage of a given amount of organopolysiloxane, it is preferableto employ a solvent solution of the siloxane mixture. Such a solutionmay contain from 0.5 to per cent by weight of the organopolysiloxanes,the preferred range for actual application to the masonry being from 1to 10 per cent by weight. The solvent employed may be practically anyorganic solvent, the only criterion being that it be capable ofdissolving the particular organosiloxanes used. Examples of suchsolvents are the aromatics such as benzene, toluene, and xylene; cyclicssuch as cyclohexanone; petroleum solvents such as kerosene, naphtha,Stoddard solvent, and mineral spirits; ethers; alcohols such as ethanoland butanol; ketones such as acetone; chlorinated solvents such ascarbon tetrachloride; and carboxylate's such as butylacetate. The choiceof solvent is thus controlled mainly by such usual considerations aseconomy, safety, drying time, and penetrating power. Preferred solventsare toluene, xylene, and mineral spirits.

The application can be carried out at extremely low temperatures with noappreciable loss in beneficial properties. The application can be madeby the conventional methods of brushing or spraying or, where individualunits are treated prior to assembly, by dipping. There is only a slightloss in beneficial properties when the masonry is wetted immediatelyafter being treated, thus a suddent and unexpected rainstorm at the siteof application can do little harm. Beneficial results are obtained evenwhen the composition is applied to wet surfaces, but it is preferablethat the application be on a dry surface. The method of this inventiondoes not clog the pores of the masonry, and hence allows the masonry to-breathe For this reason, the method is particularly adaptable toabove-grade masonry.

If-desired, the compositions of this invention may also be used inconjunction with the conventional organic materials used in treatingmasonry. The incorporation of such organic materials is sometimesmomentarily advantageous. After a short weathering period, however, noadvantages of such incorporation have been found.

In the following examples, all parts are expressed as parts by weightunless otherwise indicated. Y

The concrete blocks used for laboratory testing of the effectiveness ofthevarious treatments were in the form of cubes measuring two inches ona side. They were cast from a composition composed of 21.7 partsPortland cement, 65.2 parts sand, and 13.1 parts water. These blocksweighed about 240 to 260 grams each.

The high boiling by-product chlorosilanes for use in the followingexamples were obtained by reacting a mixture of HCl and CHsCl with amixture of silicon'and copper, at reaction temperatures ranging from250to 350 C., in accordance with the teaching of U. S. Patent No.2,488,487. Essentially all of the chlorosilanes boiling up to andincluding (CHahSiCl: were removed from the reaction products byfractional distillation. The residue from this fractionation was flashdistilled to a temperature of C. at an absolute pressure of 50 rum.mercury, to give as a distillate a mixture of the various distillableby-produced chlorosilicon compounds and hydrocarbons. This particularmixture had an analysis of 58.43 per cent by weight Cl and 18.5 per centSi, showing a ClzSi atomic ratio of 2.49:1.

Example 1 To a mixture of 420 parts of the by'product chlorosiliconcompounds and 50-parts toluene was added 227 parts of isopropanol. Thisamount of isopropanol was equivalent to 55 molar per cent of the Clpresent in the mixture of by-products. Then 34 parts of water (alsoequivalent to 55 molar per cent of the original Cl present) was added.The reaction mixture was heated to from 75 to 85 C. for three hours,then to a temperature of 150 C. at atmospheric pressure to distill of?the volatiles. The resulting product was a fluid having a viscosity ofabout 50 centistokes at 25 C. It had an analysis of 23 per cent byweight Si and 41 per cent by weight isopropoxy. This particular fluid isdesignated hereafter as fluid (A).

Slight modifications in the amount of alcohol and/or water used in theabove procedure produced fluids ranging from 20 to 200 centistokes inviscosity.

When thin films of these fluids were exposed to atmospheric moisture,non-tacky resinous films were formed. Solvent solutions were madecontaining 1 to percent of the fluids in mineral spirits. When thesolutions were applied to sections of a brick wall and allowed to dry,the brick surfaces were all highly water repellent.

Example 2 To 68 parts of the by-product chlorosilicon compound was added43 parts methanol per cent excess of theoretical). The mixture washeated to 67 C. under re flux for 8 hours, then heated to 125 C. todistill off the Example 3 Solutions containing fluids (A) or (B) weremade up in mineral spirits. Four two-inch cubic concrete blocks weredried at 80 C. for 24 hours and their individual weights noted. Theblocks were then placed in water Mt inch deep. After 24 hours the blockswere removed, blotted, and weighed. The weight gained is expressed asthe percentage of the original weight (i. e. weight gained X 100 dividedby original weight) in column I of Table II below. The blocks were thendried again for 24 hours at 80 C. and after cooling were painted withthe various solutions.

The concentration and composition of the material used on each block isshown in column II below. The blocks were then cured 12 days at C.,weighed, and again were placed in /4 inch of water for 24 hours andreweighed. The weight gained is expressed as the percentage of the drytreated weight in column III below.

To compensate for slight variations in the untreated blocks, therelative effectiveness of the treatment is shown in column IV as thevalue of III 100/I.

The test method described above is in accordance with ASTM Bulletin No.156, January 1949, entitled Testing of Masonry Water Repellents, by F.O. Anderegg. The use of inch of water in the test is roughly equivalentto the pressure exerted by a wind velocity of 20 miles per hour.

Example 4 Solutions containing 3% by weight of fluid (B) in mineralspirits were applied to concrete blocks which were given either 1, 4, 8,or 13 days curing time at 25 C. The blocks were then tested as inExample 3, with the exception that a constant level bath was used tomaintain the 34 inch water depth throughout the 24 hour When the aimmersion period. Table III shows the values obtained for each type oftreatment.

That which is claimed is:

1. The method of rendering masonry materials water repellent whichcomprises applying to said masonry an organopolysiloxane copolymerconsisting of the reaction product formed by the steps comprising (1)separating a mixture of the high boiling distillable by-products fromthe reaction of CH3C1 and Si to produce methylchlorosilanes, essentiallyall the components of said mixture of by-products having a boiling pointabove that of (CH3)zSiCl2, (2) alkoxylating said by-products with analcohol selected from the group consisting of primary and secondarylower alkyl monohydric alcohols, in amount equivalent to at least 30molar per cent of the hydrolyzable chloride present in the by-productmixture, and (3) partially hydrolyzing the alkoxylated product with anamount of water at least equivalent to the molar difference between thehydrolyzable chlorine in the original by-products and the amount ofalcohol used, but insuflicient to hydrolyze more than 70 molar per centof the total hydrolyzable groups present; said reaction productcontaining from 20 to 50 per cent by weight alkoxy.

2. The method of rendering masonry materials water repellent whichcomprises applying to said masonry an organopolysiloxane copolymercomprised of the reaction product formed by the steps comprising (1)separating a mixture of the distillable by-products of the reaction ofCHsCl and Si, essentially all the components of said mixture having aboiling point above that of (CI-Is)2SiCl2 and said reaction of CHsCl andSi having been conducted within the temperature range of 200 to 500 C.in the presence of a copper catalyst for the reaction, 2) alkoxylatingsaid by-products with an alcohol selected from the group consisting ofprimary and secondary alkyl monohydric alcohols of from 1 to 4 carbonatoms, in amount equivalent to at least 30 molar per cent of thehydrolyzable chloride present in the by-product mixture, and (3)partially hydrolyzing the alkoxylated product with an amount of water atleast equivalent to the molar difference between the hydrolyzablechloride in the original mixture of by-products and the amount ofalcohol used, but insuflicient to hydrolyze more than 70 molar per centof the total hydrolyzable groups present; said reaction productcontaining from 20 to 50 per cent by weight alkoxy.

3. A composition for rendering masonry materials water repellentcomprising an organopolysiloxane copolymer consisting of the reactionproduct formed by the steps comprising 1) separating a mixture of thedistillable by-products of the reaction of CHsCl and Si, essentially allthe components of said mixture having a boiling point above that of(CH3)2SiCl2 and said reaction of CHaCl and Si having been conductedwithin the temperature range of 200 to 500 C., (2) alkoxylating saidbyproducts with an alcohol selected from the groups consisting ofprimary and secondary alkyl monohydric alcohols of from 1 to 4 carbonatoms, in amount equivalent to at least 30 molar per cent of. thehydrolyzable chloride present in the by-product mixture, and (3)partially hydrolyzing the alkoxylated product with an amount of water atleast equivalent to the molar difference between the hydrolyzablechloride in the original mixture of byproducts and the amount of alcoholused, but insufficient to hydrolyze more than 70 molar per cent of thetotal hydrolyzable groups present; said reaction product containing from20 to 50 per cent by weight alkoxy.

4. The method of claim 2 in which the reaction of CHsCl and Si isconducted within the temperature range of 250 to 350 C.

-5. The method of claim 2 in which the alcohol employed is methanol. I

6. The method of claim 2 in which the alcohol employed is isopropanol.

7. The composition of claim 3 in which the reaction of CHaCl and Si isconducted within the temperature range of 250 to 350 C.

8. The composition of claim 3 in which the alcohol employed is methanol.

References Cited in the file of this patent.

UNITED STATES PATENTS Rust et a1 Dec. 31, 1946 Robie Sept. 6, 1949 BrickNov. 6, 1951

1. THE METHOD OF RENDERING MASONARY MATERIALS WATER REPELLENT WHICHCOMPRISES APPLYING TO SAID MASONARY AN ORGANOPOLYSILOXANE COPOLYMERCONSISTING OF THE REACTION PRODUCT FORMED BY THE STEPS COMPRISING (1)SEPARATING A MIXTURE OF THE HIGH BOILING DISTILLABLE BY-PRODUCTS FROMTHE REACTION OF CH3CL AND SI TO PRODUCE METHYLCHLOROSILANES, ESSENTIALLYALL THE COMPONENTS OF SAID MIXTURE OF BY-PRODUCTS HAVING A BOILING POINTABOVE THAT OF (CH3)2SICL2, (2) ALKOXYLATING AND BY-PRODUCTS WITH ANALCOHOL SELECTED FROM THE GROUP CONSISTING OF PRIMARY AND SECONDARYLOWER ALKYL MONOHYDRIC ALCOHOLS, IN AMOUNT EQUIVALENT TO AT LEAST 30MOLAR PER CENT OF THEE HYDROLYZABLE CHLORIDE PRESENT IN THE BY-PRODUCTMIXTURE, AND (3) PARTIALLY HYDROLYZING THE ALKOXYLATED PRODUCT WITH ANAMOUNT OF WATER AT LEAST EQUIVALENT TO THE MOLAR DIFFERENCE BETWEEN THEHYDROLYZABLE CHLORINE IN THE ORIGINAL BY-PRODUCTS AND THE AMOUNT OFALCOHOL USED, BUT INSUFFICIENT TO HYDROLYZE MORE THAN 70 MOLAR PER CENTOF THE TOTAL HYDROLYZABLE GROUPS PRESENT; SAID REACTION PRODUCTCONTAINING FROM 20 TO 50 PER CENT BY WEIGHT ALKOXY.